nerve impules

Question 1

describe the structure of a motor neurone

Answer 1

-dendrites
-axon
-myelin sheath (schwaan cells)
-nodes of ranvier (gaps)
-axon terminal

Question 2

describe how resting potential is established

Answer 2

-sodium ions diffuse in and potassium ions diffuse out
-membrane more permeable to potasium ions
-sodium potasium pump actively transports sodium ion out and potassium ions in

Question 3

how is an action potential generated

Answer 3

-stimulus arrives
-sodium ion channels open
-depolarisation
-when threshold is reached (-55) more sodium ion channels open so more sodium ions enter
-at +30 sodium ion channel close and pottasium ion channels open
-pottasium leaves repolarisation
-more pottasium leaves (hyperrepolarisation)
-sodium pottasium pump restores resting potential at -70

Question 4

all or nothing principle

Answer 4

action potential is only generated when threshold is reached

Question 5

importance of refractory period

Answer 5

-maintain acion potential in one direction
-limits number of impulse transmission
-action potential is seperate from another
-

Question 6

how does myelination of n axon affct spped of transmission

Answer 6

-insulates axon
-jumps from node to node (saltatory conduction)
-doesnt have to generate along the whole length of axon

Question 7

how does axond diameter affect speed of conduction

Answer 7

-wider axon+faster speed-less leakage of ions

Question 8

how does temperature affect speed of conduction

Answer 8

-higher temp means increase in movement of ions
-ions diffuse faster
-faster enzyme activity so more atp for more active transport